Paraoxonase (also referred to as human serum paraoxonase or PON1) is a Ca2+-dependent glycoprotein having a molecular weight of about 45 kDa which exists as one of protein components that constitute high density lipoprotein (HDL) in blood. PON is known as a serum enzyme that degrades oxon, organophosphorous compounds, and aromatic carboxylic acids such as sarin which is a nerve gas, and can be used as an antidote for these substances. In recent years, physiological activities of PON are being elucidated. For example, antiarteriosclerotic action, antioxidative action and the like have been reported (Non-patent documents 1 and 2, Patent document 1).
As for purification of PON, methods of employing a blue agarose treatment and a DEAE-type anion exchanger treatment in combination were reported (Non-patent documents 3 and 4). According to these reports, PON was purified under the coexistence of glycerol and a polyoxyethylene alkyl phenyl ether-type non-ionic surfactants (specifically, Emulgen and Nonidet P-40, both are trade names). However, the documents do not disclose use of other substances such as, for example, 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (henceforth also referred to as CHAPS). Further, CHAPS was reported to be added in a serum specimen containing PON to maintain the enzymatic activity (Patent document 2). However, this report is not related to purified PON.
Some reports were made which suggest medicinal applications of PON. For example, a report was made which suggests relationships between an amount of PON in vivo and angina pectoris, myocardial infarction, and cerebral infarction (Patent document 2). Patent document 3 is a report relating to a disorder resulting from ischemia reperfusion in connection with Apo-A1. In the report, PON is suggested to be effective for the disorder resulting from ischemia reperfusion like Apo-A1, however, the effect thereof was not specifically disclosed.
As described above, PON is at present merely suggested to have some medicinal usefulness. Almost no report has been made as to means for stably supplying PON for medical uses.    Patent document 1: International Patent Publication WO00/30425    Patent document 2: Japanese Patent Unexamined Publication (KOKAI) No. 2000-333674    Patent document 3: International Patent Publication WO03/97696    Non-patent document 1: J. Clin. Invest., Vol. 101, pp. 1581-1590, 1998    Non-patent document 2: Nature, Vol. 394, pp. 284-287, 1998    Non-patent document 3: Drug Metabolism and Disposition, Vol. 19, No. 1, pp. 100-106,    Non-patent document 4: Biochemistry, Vol. 30, pp. 10133-10140, 1991    Non-patent document 5: Proc. Natl. Acad. Sci. USA, Vol. 92, pp. 7187-7191, 1995    Non-patent document 6: J. Lipid Research, Vol. 42, pp. 951-958, 2001    Non-patent document 7: Stroke, Vol. 20, pp. 1037-1043, 1989    Non-patent document 8: Journal of Cerebral Blood Flow and Metabolism, Vol. 20, pp. 1311-1319, 2000